Telephone-exchange system.



C. L. GOODRUM. -TEL'EPHONE EXCHANGE SYSTEM.

APPLICATION FILED APR. 9, 1915- latent-ed May 30,1916.

2 SHEETSSHEET 2- li m wmw \B 3 1 l V/fnesses:

Char/es L. Good/um, y

A/ij/ 622% Ma, fly

- and test contacts UNITED STATES PATENT OFFICE.

CHARLES'L. GOODRUM, OF NEW YORK, N. Y., ASSIGNOR, BYMESNE ASSIGNMENTS, TO WESTERN ELECTRIC COMPANY, INCORPORATED, A CORPORATION OF NEW YORK.

TELEPHONEEXCHANGE SYSTEM.

Specification of Letters Patent.

Patented Way 30, 1916.

Application filed April 9, 1915. Serial No. 20,183. i

To all whom it may concern:

Be it known that I, CHARLES L. GooDRUM, a citizen of the United States, residing at New York, in the county of New York and State of New York, have invented certain new and useful Improvements in Telephone- .Exchange Systems, of which the following is a full, clear, concise, and exact description.

This invention relates to telephone exchange systems employing non-numerical switches for associating calling lines with idle connecting circuits. Its object is to provide an improved metering circuit arrangement for such systems.

In accordance with this invention. the meter individual to each line is connected with the test terminal thereof in the non numerical switch, and has a magnet adapted to cause the same to record a call only upon the receipt of a predetermined number of impulses and then only with the cooperation of a slow relay in circuit therewith. The invention is shown as embodied in a machine switching telephone system wherein the lines are provided with multiple line in automatic finder switches. The message register magnet and the ratchet wheela plurality of steps. Thus the cutoff relay of each line are connected to the multiple test contacts of such line in the finders. the cutoff relay being slow acting, and when energized, forcing a. retaining pawl for the driving ratchet of the counting train of the message register into engagement with said ratchet wheel. The

counting train is also provided with a detent and cooperating stops constructed and arranged to interlock, and thus to maintain thecounting train advanced to record a call only when the meter magnet has advanced as the test brush of the finder successively engages the test contacts of noncalling lines in seeking the calling line, while the meter magnets of such lines may receive an impulse of current, a call will not be recorded on the counting train since the (lecnergization' of the cutoff relay, following the engagement of the test brush with the corresponding, test terminal, permits the retaining pawl for the ratchet of the counting train to fallback, whereupon the counting train restores itself. However, when the finder has connected to the calling line and the connection has been extended either by a chain of automatic switches or by any equivalent means, the response of the called party actuates means for transmitting to the meter magnet a number of impulses sufficient to advance the counting train to record a completed connection; that is until the detent referred to engages the succeeding stop and thus locks the counting train advanced independently of the retaining pawl, which falls back when the cutoff relay is deenergized after the connection has been disestablished. r

Referring to the drawings-Figure 1 is a diagram of a line finder circuit embodying my invention, the brushes and cooperating contacts of a first selector being also shown, and Fig. 2 is a diagram of a connector circuit operating therewith.

The subscribers lines a b are divided into groups. each terminating as calling lines in multiple contacts 139, 140 of a group of finders like that shown diagrammatically in Fig. 1 and as called lines in multiple contacts 240, 241 of a group of-connectors like that shown diagrammatically in Fig. 2. The closure of the line circuit by the removal of the receiver from its switchhook by a calling party causes an idle line finder to be set in motion to connect with such line. The finder then in a primary, movement, selects the group containing the calling line and in a secondary movement, the particular line in such group which is calling. The calling line is thus extended to a first selector, whose brushes only are shown, which is set by the calling party by means of his sender 165 in the well known manner to extend the calling line to the connector shown in Fig. 2 which is in turn caused to connect with the desired line by a primary and secondary movement under the control of the sender manipulated by the calling party.

A general description of the mode of operation having been given, it is thought the invention will be readily understood from a detailed description of the operation of interconnecting two substations.

' Upon the removal of the receiver 101 at substation A, the line relay 102 is energized and as its armature and front contact closes the following circuit for relay 108 preliminary to starting the line finder in motion: free pole of battery, left-hand winding of relay 102, conductor 1.86, left-hand brushes'114, 115,116, also carries a brush 117 adapted to wipe over segments 122, disposed in a circle, one for each line group, during the primary movement of the finder in seeking the calling line group, in case the finder apportioned to such group is busy, as will hereinafter appear. The contact arm 117 is connected by conductor 118, sideswitch arm 119 and conductor 120 to the escapement magnet 121 of the side-switch and from thence by conductor 122, conductor 108, primary magnet 105, conductor 107, to battery. Thus, in case the finder shown in Fig. 1 which is the one apportioned to this group be idle, brush .117 is in contact with metallic segment 122 of this group as shown which-has been grounded by the attractionof the right hand armature of relay 103 of the group of lines to which the calling one belongs. Therefore escapement magnet 121 is immediately energized upon the energization of group relay 103 and releases the side switch into the second position in the well known manner. In this position of the side-switch the secondary magnet 111 causes the brush rodto move its wipers 114, 115 and116 over the group of lines in search of the calling line. The circuit for the secondary magnet 111 is as follows: free pole of battery, conductor 107, secondary stepping magnet 111, conductor 123, side switch arm 109, and its second contact, conductor 110, armature and back contact of secondary stepping magnet 111, conductor 124, armature and front contact of escapement magnet 121, (now energized), conductors 112, 125, right-hand armature and front contact of relay 104, conductor 113, right-hand armature and front contact of relay 103 to ground.

The secondary stepping magnet .111 'now intermittently interrupts its circuit and a pawl (not shown), carried by its armature moves the shaft of the line finder carrying the brushes 114, 115, 116 to cause said brushes. to wipe over the terminals 139, 140, 126 of the group to which the calling line belongs. During this operation, side-switch arm 127 connects ground to brush 116 over the following circuit; right-hand armature and front contact of relay 103, conductor 113, right-hand armature and front contact of relay 104, conductor 125, conductor 128,

side-switcharm 127, conductor 129,.arm 130 of switch S, conductor 131 to said brush 116. Thus, as'the brush 116 engages the terminals 126, the cut-off relays 132 are successively operated. It will be noted that the line relay 102 of the calling line is locked up in series with relay 103, this circuit being controlled at the back contact of the cut-off relay 132 of the calling line. Thus, when the 'cut-ofi relay 132 of the calling line is reached and operated by the brush 116, the circuit of relay 103 is broken and its right-hand armature falls back and opens the stepping circuit for the secondary magnet 111 just traced, thus stopping the finder brushes 114, 115, 116 upon the terminals 140, 139, 126 of the calling line. The deenergization of relay 103 causes the deenergization of escapement magnet 121 which releases the side switch into position 3. Side-switch arm 127 in position 3 renders this line busy in the connectors by ground ing conductor 129 connected to brush 116 which is now in engagement with terminal 126, this terminal being multiplied to the test terminals of this line in the connectors.

In position 3, the calling line is extended to the group selector, whose brushes 116, 117 only are shown. Afterthis switch has been set in the well-known manner by the operation of the calling partys sender 165, and has automatically picked out an idle trunk terminating in a connector, the relay 200 of such connector is operated over the following circuit; free pole of the battery (Fig. 2), left-hand windingof relay 200, side-switch arm 202, conductor 203, terminal 169, brush 167 of the selector, polarized relay 137, sideswitch arm 135, conductor 138, brush 115, contact 139, line conductor a, substation set of calling party A, line conductor 1), contact 140, brush 114, conductor 141, brush 134, conductor 142, brush 166, contact 168, conductor 204, side-switch arm 201, conductor 205, right-hand windingof relay 200 to ground. The relay 137 is polarized so as not to operate by the closure of this circuit. Relay 200, upon'its energization, closes a circuit for slow acting relay 209 at its armature and front contact. Relay 209, at 'its right-hand armature and front contact prepares a circuit for the primary stepping magnet 210. The calling subscriber now operates his sender 165 and interrupts the circuit of relay 200 a number of times, corresponding to the second digit of the number of the called line. Each time the armature of relay 200 closes its back contact a circuit for primary stepping magnet 210 is closed as follows: free pole of battery, magnet 210, side-switch arm 211, conductors 215, 212, right-hand armature and front contact of slow relay 209, conductor 213, armature and back contact of relay 200, to ground. The magnet 210 thus moves the brush rod in a primary direction by a pawl engaging a ratchet on the connector shaft (not shown), to pick-out the group in the connector to which the called line belongs. Upon the first break in the line circuit and the consequent falling back of the armature of relay 200, a circuit was closed for slow-acting escapement magnet 214, as follows: free pole of battery, magnet 214,- conductor 212, armature and front contact of relay 209, conductor 213, armature and back contact of relay 200 to ground. This magnet being slow-acting, remains energized until the closure of the line circuit at the end of this series of breaks, whereupon it falls back and moves the side switch into position 2. Arm 211 thereof, in position 2, prepares a circuit for the secondary magnet 216. Upon the operation of the sender 165 in transmitting the last digit of the wanted number, relay 200 is intermittently de'e'nergized and the magnet 216 moves the connector brushes to the terminals of the wanted line, thecircuit being as folthen de'e'nergized and moves the side switch 214, conductor 215, arm 211, conductors 218,

219, armature and back contact of ringing control relay 220, to ground. The escapement magnet at its right-hand armature and front contact closes the ringing circuit as follows; free pole of ringing generator 221, conductor 222, ringing control relay 220, conductor 223, right-hand armature and front contact ofescapement magnet 214, conductor 224, side-switch arm 225, conductor 226, brush 207, terminal 241, line conductor a, bell 251, line conductor 5, terminal 240, brush 206, conductor 227, arm 228, conductor 229, conductor'230, armature and front contact of relay 200, to ground.

Then the called party answers, themargin"f elay 220 is energized in the wellknj manner and opens the circuit of the escapement magnet 214, whereupon the escapement magnet releases the side switch into position 4, thus opening the ringing circuit. Relay 231 is now energized and talking current is supplied to the called line through the windings of this relay. It will be noted that when the side switch moves into position 4 upon the response of the called party, arms 201, 202 of the side switch reverse the connection of the battery supplied to the calling party. The polarized relay 137 thereupon operates and closes the driving circuit of the motor magnet 144 of switch S to set the same in motion. This driving circuit is as follows; free pole of battery, motor magnet 144, its armature and back contact, conductor 172, armature 146, to ground. The magnet 144 makes and breaks its own circuit, and the pawl 170 carried by its armature steps the arm 130 over the segments .145 of switch S. The retaining pawl 146 is allowed to move into engagement with the ratchet wheel 171 of switch S upon the lirst step of the finder from its normal position. Since the arm 130 is, connected to ground by conductor 129 and side-switch arm 127, impulses will be sent to the metermagnet 147 as said arm advances, the circuit being as follows; free pole of battery, eut-ofi' relay 132, conductor 1.48, meter magnet 147, conductor 149, contact 126, brush 116, conductor 131, segments 145, arm 130, conductor 129, side-switch arm 127 to ground. The meter magnet 147 thus by means of the pawl carried by its armature 151, engaging ratchet wheel 152, rotates the shaft 153 of the message register a suilicient distance so that the detent 154 engages notch 155 in the large ratchet wheel 156, thus counting the call. The arm 130 of switch S is arrested after having trans- .miited the required number of impulses by engaging a stop 190 of insulating material mounted on spring 191, which spring by closing contact 175 short circuits the polarized relay 137, thus removing it from the talking circuit. In deenergizing, this relay removes ground from conductor 172.

' The cut-off relay 132 is made slow-acting so that its right-hand armature will maintain the retaining pawl 157 in contact with the ratchet wheel 152, notwithstanding the breaks in its circuit. Since the armature 151 of the meter magnet 147 is held attracted during conversation, there is no liability of testing finders or connectors falsely operating the meter.

Upon the conclusion of the conversation and the hanging up of the receiver by the calling party, relay 200 is decnergized and at its back contact closes the circuit of the finder release magnet 106 as follows; free pole or battery (Fig. 1), release magnet 106, conductors 159, 160, armature and back contact of relay 133, conductor 161, off-normal contact 162 of the finder, conductor 158,

busy as a calling line, said test terminal is the left-hand armature of relay 231; from that point, instead of continuing by wa the back contact of said armature, it continues by way of front contact of said armature, conductors 234, 2l2,'armature and front contact of slow relay 209, conductor 213, armature and back contact of relay 200 to ground, relay 209 holding up for an instant after the armature of relay 200 falls back. The release magnet of the selector (not shown) would be in parallel with re lease magnet 106 of the finder and would release the selector when the finder is released. The finder in its restoring move ment removes the holding pawl 146 from ratchet wheel 171 of switch S, whereupon it is restored by a spring (not shown). The armature of release magnet 1.06 upon its at tractive movement restores the finder-side switch, in the well-known manner, and locks itself up at its armature and front contact.

and finder off-normal contact 162. vWhen the .finder reaches its normal position this circuit is opened at such off-normal contact to release magnet 106.

\Vhen the called party hangs up his receiver the connector release magnet 236 is energized over the following circuit; free pole of battery (Fig. 2) left-hand winding of magnet 236, conductor 237, right-hand armature and back contact of relay 231, conductor 252, side switch arm 238, conductors 239, 219, armature and-back contact of relay 220 to ground. Release magnet 236 upon its energization restores the side switch in the well-known manner. Magnet 236, however, remains energized over the following circuit; free pole of battery, left-hand winding of said magnet, conductor 237, right-hand armature and back contact of relay 231, side-switch arm 238, (now in positions 1, 2 or 3), conductor 244, connector off-normal contact 245, conductor 246, left-hand armature and back contact of relay 209, conductor 232, left-hand armature and back contact of relay 231,'conductor 233, righthand armature and back contact of relay 209, conductor 213, armature and back contact of,relay 200 to ground This circuit maintains release magnet 236 energized until the connector reaches its normal position, when it is deenergized by the opening of oil'- normal contact 245.

In case the Wanted line is busy, as a called line its test terminal 242 is grounded by side-switch arm 246 of another connector; if

grounded by side-switch arm 127 of another finder. In this event, when under thecontrol of the sender of the calling party, the connector selects such busy line, the connector is immediately released and a busy signal is'given to the calling party.

It will be recalled that when the line circuit is permanently closed at the end of the last or units series of interruptions, the escapement magnet 214 of the side switch of the connector is deenergized and releases the side switch into position 3 to signal the selected line. Its left-hand armature is so arranged, however, that it closes its back contact before the side switch is released. The following circuit is then closed for release magnet 236 of the connector, if ground is present on test terminal 242 of the selected line, which will be the case if the line is busy; free pole of battery, left-hand winding of release magnet 236, conductor 237, right-hand armature and back contact of relay 231, conductor 252, side-switch arm 238and its second contact, conductor 244, connector off-normal contact 245, left-hand armature and back contact of escapement magnet 214, conductor 247, side-switch arm 246 and its secondfcontact, conductor 248, brush 208, contact 242, to ground either at the side-switch arm 246 and its third or fourth contact of the connector connected to amultiple contact of this line, or at the sideswitch arm 127 and its third contact of a finder connected to a multiple contact of this line. The release magnet 236 at its left-hand armature and front contact locks itself over thefollowing circuit; free pole of battery, right-hand locking winding, left-hand armature and front contact, conductors, 249, 230 armature and front contact of relay 200 to ground. The release magnet 236 at its right-hand armature and front contact applies a tone over conductors 250, 203 to the calling line.

When the calling party hangs up his receiver, relay 200 is deenergized, opening at its armature and front contact the locking circuit of magnet. 236, and at its back con-' tact closing the following circuit to release the selector and finder; ground armature and back contact of relay 200, conductor 213,1'ight-hand armature and back contact of relay 209, conductor 233, left hand armature and back contact ofrelay 231, conductor 232, contact 174 brush 173 of the selector, conductor 158, off-normal contact 162, conductor 161, right-hand armature and back contact of relay 133, conductor 1 60, release magnet 106 to free pole of battery.

If a finder having been set in motion fails to connect with the calling line, its brush shaft closes a contact 17 6 upon the beginning of the eleventh secondary step thereof. This causes the finder release circuit to be Thus the'connector is released.

closed as follows: free ole of battery, re-

lease magnet 106, con' uctor 159, contact 176, ground, whereupon the release magnet locks itself up at its armature and front contact over the following circuit: free pole of battery, magnet 106, conductor 159,-conductor 160, right-hand armature and back contact of relay 133, conductor 161, offnormal contact 162, conductor 158, armature and front contact of magnet 106 to round. Since this circuit leads through finder olfnormal contact 162, it-is opened when the finder reaches its normal position. The apparatus is now in normal positionready to set up another call.

The finders are allotted to the calling lines by a starter wire. As stated a finder is allotted to each line group whose contact brush117 normally rests on a segment 122 individual to such group. In this position such finder is positioned to wipe over the terminals of its line group without a preliminary group selecting movement. That is, the brushes are slipped in the various finders in which the groups appear. Thus no primary movement of the brush rod of the finder allotted to the calling line group is necessary in order to connect with a calling line therein, as has just been shown. If, however, the finder shown in Fig. 1 had been busy, the starter wire 125 would have been extended by side switch arm 109 (position 3), to the next idle finder, which would first be given a primary movement by means of its primary stepping magnet corresponding to 105 of Fig. 1 to place the finder in a position to move its brushes over the terminals of the calling group. The starting circuit for such finder would then be as follows: ground, right-hand armature and front contact of group relay 103, conductor 113, right-hand armature and front contact of relay 104, starting conductor 125, conductors112, 178, armature and back contact of primary magnet 105, armature and back contact of secondary magnet 111, con ductor 110, side-switch arm 109 and its third contact, conductor 180, to the primary magnet of the next idle finder. From this point the operation may be traced by reference to Fig. 1 and assuring the finder shown therein to be idle. The circuit then continues by conductor 181, (left-hand side of Fig. 1), left-hand armature and back contact of relay 104, conductors 182, 183, relay 133 to free poleof battery. The relay 133 immediately opens at its left-hand armature and back contact the circuit of conductor 184 of this line group, thus removing the control of its group starting relay 103 therefrom and thereby preventing interference. In parallel with'this circuit, a circuit for the primary magnet 105 of such finder is closed. This circuit is the same as that-just traced up to and including conductor 182. From this point it continues by way of the righthand armature and back contact of slowacting relay 104, conductors 125, 112, 178, armature and back contact of primary magnet 105, armature and back contact of secondary magnet 111, conductor 110, sideswitch arm 109,- conductor 185, primary magnet 105, conductor 107 to free pole'of the battery. The primary stepping magnet 105 of this finder makes and breaks its own circuit, causing the pawl carried thereby to rotate the shaft (not shown), until brush 117 encounters the segment 122 of the calling line group, grounded by the energization of the relay 103 of such group. The escapement magnet 121 of the side switch of such finder is then energized, releasing the side switch into position 2, the side switch arm 109 of such finder opening the circuit of the primary stepping magnet 105 thereof and substituting the secondary stepping magnet 111 to move the finder brushes over the terminals of the selected group in search.

of the calling line. From this point on the operation is the same as that already traced, except that when the cut-off relay of the calling line is reached and deenergizes the group relay 103 of such group, this relay opens the circuit of relay 133 of Fig. 1 which, at its left-hand armature and back contact restores the control of relay 103 to its group of subscribers. When a call comes in from a line of another group whose finder is busy, and the finder shown in Fig. 1 is also busy, the starter wire 121 is led to the next idle finder. Since this circuit includes side-switch arm 109, which in that case is in position 3, should subscriber A hang up his receiver at this time, the finder in releasing would restore the side-switch arm 109 and thus break the starting circuit. To prevent this, the release circuit of the finder of Fig. 1 is maintained open at the back contact of relay 133 and this relay is deenergized only when the finder which is operating has connected to the calling line.

While in the present embodiment of the invention, the meter is operated upon the response of the called party, it is within the scope of the inventionto operate the meter at some other stage in the process of building up or disestablishing the connection. When the invention is applied to semi-automatic systems the switch S may be under control of the operator at the central office.

What is claimed is:

1. In a telephone exchange system, the combination with telephone lines, connecting circuits, non-numerical switches for extending said lines to said connecting circuits, test terminals for said lines in said switches. call registers included in circuit with said test terminals, an operating magnet for each register, of a slow relay in circuit therewith controlling the holding pawl of said register, and means controlled by said magnet and relay for operating said register upon the receipt of a plurality of impulses by said magnet.

2. In a telephone exchange system, wherein a calling line is associated with a connecting circuit by a non-numerical switch, the combination with a call register for each line having a pawl and ratchet, a magnet for operating said pawl, a retaining pawl for said ratchet, and a detent and cooperating stops constructed and arranged to interlock only when said magnet has advanced said ratchet a plurality of steps, means for transmitting the required number of impulses to said magnet to cause said detent to engage the succeeding stop, of a slow relay in circuit with said magnet, said slow relay controlling the engagement of said retaining pawl with said ratchet.

3. In a telephone exchange system wherein calling lines terminate in a finder, the combination with a call register for each line having a pawl and ratchet, a magnet for, operating said pawl, a retaining pawl for said ratchet and a detent and cooperating stops constructed and arranged to interlock only when said magnet has advanced said ratchet a plurality of steps, means for transmitting the required number of impulses to said magnet to cause said detent to engage the succeeding stop, of a slow relay in circuit with said magnet, said retaining pawl being normally inoperative but during the transmission of said impulses being forced by the armature of said slow relay into engagement with'said ratchet to hold the train advanced.

4. In a telephone exchange system, wherein calling lines terminate in' a finder, the combination with a call register for each line having a pawl and ratchet, a magnet for operating said pawl, a retaining pawl for said ratchet, a detent and cooperating stops constructed and arranged to interlock only when said magnet-has advanced said ratchet a plurality of steps,.means for transmitting the required number of impulses to said magnet to cause said detent to engage the succeeding stop, of a slow acting cutoff relay in circuit with said magnet, said retaining I pawl being normally inoperative but durthe called subscriber to operate the register,

' of the calling party to record a call.

6. In a telephone exchange system, the combination-with a plurality of subscribers lines, means for interconnecting the same including a finder, wherein each of said lines terminates in line contacts, a test contact for each line, said finder having line and'test brushes for engaging said line and test contacts, means for causing said test brush to engage said test contacts successively, a message register foreach line, a magnet therefor connected to the test contact of such line, said magnet being adapted to advance said register a complete step only upon the receipt of a. predetermined number of impulses, means for causing said finder to connect with a calling line, means for sending the required number of impulses to operate the register, and a magnet operated when'the called party responds to operate said means.

In witness whereof, I hereunto subscribe my namev this 8th day of April, A. D. 1915.

CHARLES L. GOODRUM. 

